Integrated MIMO and SAR radar antenna architecture for self driving cars

ABSTRACT

A radar system includes a split-block assembly unit comprising a first portion and second portion, where the first portion and the second portion form a seam. The radar system further includes a plurality of ports located on a bottom side of the second portion opposite the seam. Additionally, the radar system includes a plurality of radiating elements located on a top side of the first portion opposite the seam. The plurality of radiating elements is arranged in a plurality of arrays. The plurality of arrays includes a set of multiple-input multiple-output (MIMO) transmission arrays, a set of synthetic aperture radar (SAR) transmission arrays, and at least one reception array. Further, the radar system includes a set of waveguides configured to couple each array to a port.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Radio detection and ranging (RADAR) systems can be used to activelyestimate distances to environmental features by emitting radio signalsand detecting returning reflected signals. Distances to radio-reflectivefeatures can be determined according to the time delay betweentransmission and reception. The radar system can emit a signal thatvaries in frequency over time, such as a signal with a time-varyingfrequency ramp, and then relate the difference in frequency between theemitted signal and the reflected signal to a range estimate. Somesystems may also estimate relative motion of reflective objects based onDoppler frequency shifts in the received reflected signals. Directionalantennas can be used for the transmission and/or reception of signals toassociate each range estimate with a bearing. More generally,directional antennas can also be used to focus radiated energy on agiven field of view of interest. Combining the measured distances andthe directional information allows for the surrounding environmentfeatures to be identified and/or mapped. The radar sensor can thus beused, for instance, by an autonomous vehicle control system to avoidobstacles indicated by the sensor information.

Some example automotive radar systems may be configured to operate at anelectromagnetic wave frequency of 77 Giga-Hertz (GHz), which correspondsto millimeter (mm) electromagnetic wave length (e.g., 3.9 mm for 77GHz). These radar systems may use antennas that can focus the radiatedenergy into beams in order to enable the radar system to measure anenvironment with high accuracy, such as an environment around anautonomous vehicle. Such antennas may be compact (typically withrectangular form factors; e.g., 1.3 inches high by 2.5 inches wide),efficient (i.e., there should be little 77 GHz energy lost to heat inthe antenna, or reflected back into the transmitter electronics), andcheap and easy to manufacture.

In some scenarios, efficiency may be difficult to balance with cheap andeasy manufacture. Some cheap and easy to manufacture options may involveintegrating an antenna into a circuit board (e.g., with a “series-fedpatch array”), which is used by many off-the-shelf automotive radars.However, such antennas may lose much of their energy into heating up thesubstrate of the circuit board. Antennas with the lowest loss mayinclude all-metal designs, but typical all-metal antennas, such asslotted waveguide arrays, can be difficult to manufacture with the smallgeometries compatible with 77 GHz operation.

SUMMARY

In one aspect, the present application describes a radar system. Theradar system includes a split-block assembly having a first portion andsecond portion. The first portion and the second portion form a seam,where the first portion has a top side opposite the seam and the secondportion has a bottom side opposite the seam. The radar system alsoincludes a plurality of ports located on a bottom side of the secondportion. The radar system further includes a plurality of radiatingelements located on a top side of the first portion. The plurality ofradiating elements is arranged in a plurality of arrays. The pluralityof arrays include a set of multiple-input multiple-output (MIMO)transmission arrays, a set of synthetic aperture radar (SAR)transmission arrays, and at least one reception array. Additionally, theradar system includes a set of waveguides in the split-block assemblyconfigured to couple each array to a port.

In another aspect, the present application describes an antennaconfiguration for a vehicle-mounted radar system. The antennaconfiguration includes four multiple-output (MIMO) transmission antennaarrays, each MIMO array configured as a six by ten array. The antennaconfiguration also includes four synthetic aperture radar (SAR) arraystransmission antenna arrays, each SAR array configured as a six by tenarray. Further, the antenna configuration includes a SAR reception arrayconfigured as a six by ten array. Additionally, the antenna unitincludes a uniform linear array configured as a sixteen by ten array.

In yet another aspect, the present application describes avehicle-mounted radar system. The vehicle-mounted radar system includesfour multiple-output (MIMO) transmission antenna arrays, each MIMO arrayconfigured having a broadside beam width of approximately 90 degrees.The vehicle-mounted radar system further includes four syntheticaperture radar arrays (SAR) transmission antenna arrays, each SAR arrayhaving a beam width of approximately 45 degrees pointed at an angle of22.5 degrees. Additionally, the vehicle-mounted radar system includes aSAR reception array configured having an electronically steerable beam.Also, the vehicle-mounted radar system includes a uniform linear arrayconfigured having an electronically steerable beam.

Additionally, the SAR and MIMO antennas may be strategically staggeredin elevation, as well as in azimuth, to allow SAR and MIMO operationmodes to capture three-dimensional data. Furthermore, in one example,the positioning (i.e. angular pointing and the beamwidths) of the radarunits are designed to allow the use of at least four such radars at thefour corners of a vehicle of a pointed in a manner to provide full 360degree radar coverage.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the figures and the followingdetailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates an integrated MIMO and SAR radar antennaarchitecture.

FIG. 2 illustrates another view of an integrated MIMO and SAR radarantenna architecture.

FIG. 3 illustrates an expanded view of an integrated MIMO and SAR radarantenna architecture.

FIG. 4 illustrates an internal view of an integrated MIMO and SAR radarantenna architecture.

FIG. 5A illustrates a first layer of an example antenna, in accordancewith an example embodiment.

FIG. 5B illustrates a second layer of an example antenna, in accordancewith an example embodiment.

FIG. 5C illustrates an assembled views of an example antenna, inaccordance with an example embodiment

FIG. 5D illustrates an assembled views of an example antenna, inaccordance with an example embodiment.

FIG. 5E illustrates conceptual waveguide channels formed inside anassembled example antenna, in accordance with an example embodiment.

FIG. 6A illustrates a network of wave-dividing channels of an exampleantenna, in accordance with an example embodiment.

FIG. 6B illustrates an alternate view of the network of wave-dividingchannels of FIG. 6A, in accordance with an example embodiment.

FIG. 7A illustrates an example wave-radiating portion of an exampleantenna, in accordance with an example embodiment.

FIG. 7B illustrates an example offset feed waveguide portion of anexample antenna, in accordance with an example embodiment.

FIG. 7C illustrates an example waveguide termination comprising couplingport, attenuation components, and a coupling component, that uses PCBbased absorbers.

FIG. 8A illustrates an example two-dimensional beamforming network, inaccordance with an example embodiment.

FIG. 8B illustrates an example three-dimensional beamforming network, inaccordance with an example embodiment, showing a power dividing sectionand a phase adjustment lens.

FIG. 8C illustrates an example three-dimensional beamforming networkfeeding an array of antennas, in accordance with an example embodiment.

FIG. 8D illustrates an example three-dimensional beamforming networkwith short wall coupling, in accordance with an example embodiment.

FIG. 8E illustrates an example three-dimensional beamforming networkwith short wall coupling, in accordance with an example embodiment.

FIG. 8F illustrates an example short wall coupler, in accordance with anexample embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying figures, which form a part hereof. In the figures, similarsymbols typically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, figures, and claims are not meant to be limiting. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the scope of the subject matter presented herein. It willbe readily understood that the aspects of the present disclosure, asgenerally described herein, and illustrated in the figures, can bearranged, substituted, combined, separated, and designed in a widevariety of different configurations, all of which are explicitlycontemplated herein.

The following detailed description discloses an apparatus having anintegrated MIMO and SAR radar antenna architecture. The MIMO and SARradar antenna architecture may include a plurality of “dual open-endedwaveguide” (DOEWG) antennas. In some examples, the term “DOEWG” mayrefer herein to a short section of a horizontal waveguide channel plus avertical channel that splits into two parts, where each of the two partsof the vertical channel includes an output port configured to radiate atleast a portion of electromagnetic waves that enter the antenna.Additionally, a plurality of DOEWG antennas may be arranged into anantenna array. The MIMO and SAR radar antenna architecture describedherein may include a plurality of antenna arrays.

An example antenna architecture may comprise, for example, two metallayers (e.g., aluminum plates) that can be machined with computernumerical control (CNC), aligned properly, and joined together. Thefirst metal layer may include a first half of an input waveguidechannel, where the first half of the first waveguide channel includes aninput port that may be configured to receive electromagnetic waves(e.g., 77 GHz millimeter waves) into the first waveguide channel. Thefirst metal layer may also include a first half of a plurality ofwave-dividing channels. The plurality of wave-dividing channels maycomprise a network of channels that branch out from the input waveguidechannel and that may be configured to receive the electromagnetic wavesfrom the input waveguide channel, divide the electromagnetic waves intoa plurality of portions of electromagnetic waves (i.e., power dividers),and propagate respective portions of electromagnetic waves to respectivewave-radiating channels of a plurality of wave-radiating channels. Thetwo metal layers may be assembled together to form a split-blockassembly.

In various examples, the power dividing elements of the antennaarchitecture may be a three-dimensional dividing network of waveguides.The three-dimensional dividing network of waveguides may use waveguidegeometry to divide power. For example, the feed waveguides may have apredetermined height and width. The predetermined height and width maybe based on a frequency of operation of the radar unit. Thethree-dimensional dividing network may include waveguides that differ inheight and/or width from the predetermined height and width of the feedwaveguides in order to achieve a desired taper profile.

In the present disclosure, feed waveguides that provide a signal toradiating elements may be divided between the top and bottom portions ofthe split-block assembly. Further, the feed waveguides may all belocated in a common plane where the midpoint of the height of feedwaveguides is common for all of the feed waveguides. Thethree-dimensional dividing network of waveguides may be located partlyin the same plane as the feed waveguides and partly in at least oneother plane. For example, the entire height of a portion of thethree-dimensional dividing network of waveguides may be machined intoeither the first or second portion of the split-block assembly. When thetwo block pieces are brought together, a surface of the other blockportion may form an edge of the portion or the three-dimensionaldividing network of waveguides that has its height fully in one of thetwo block sections. In some examples, the vertical portion of thesewaveguide cavities and cuts are symmetric with respect to the splitblock seam.

In another example, the power dividing elements may be a two-dimensionaldividing network of waveguides. The two-dimensional dividing network ofwaveguides may use waveguide geometry to divide power. For example, thefeed waveguides may have a predetermined height and width. Thepredetermined height and width may be based on a frequency of operationof radar unit. The two-dimensional dividing network may includewaveguides that differ in width from the predetermined width of the feedwaveguides in order to achieve the desired taper profile. Thus, thedividing network may have a geometry that is varied compared to the feedwaveguide geometry.

In the present disclosure, the feed waveguides may be divided betweenthe top and bottom portions of the split-block assembly. Further, thefeed waveguides and the two-dimensional dividing network may all belocated in a common plane where the midpoint of the height of feedwaveguides is common for all of the feed waveguides. When the two blockpieces are brought together, the two half-height waveguide portions maycouple and form a full-height waveguide.

In yet another example, the power dividing elements may be athree-dimensional dividing network of waveguides. The three-dimensionaldividing network of waveguides may form hybrid couplers to divide theelectromagnetic energy. In practice, the three-dimensional dividingnetwork may include waveguides that have a portion of the length of arespective waveguide adjacent to the length of a portion of anotherwaveguide. The waveguides may have adjacent short walls. The twowaveguides may be separated by a thin metal sheet. A coupling aperturemay be formed based on cutouts, holes, or spaces in the thin metal sheetto allow electromagnetic energy to couple from one waveguide to theadjacent waveguide.

Additionally, in a region that forms a short wall hybrid coupler, afull-height waveguide may be formed in a top block portion and afull-height waveguide may be formed in a bottom block portion. A thinmetal layer may be located at the seam between the two block portions toform both an edge of the respective waveguide of the dividing networkand a coupling aperture. Holes, cuts, perforations, or areas without thethin metal layer may form the aperture by which electromagnetic energymay couple from one waveguide of the dividing network to anotherwaveguide of the dividing network.

Both the three-dimensional dividing network of waveguides and thetwo-dimensional dividing network of waveguides presented herein allows apower dividing beamforming network to be constructed to be more compact(i.e. fit in a smaller volume) than traditional beamforming networks.Further, the three-dimensional dividing network and the two-dimensionaldividing network of waveguides presented herein may be constructed withreactive components. In practice, a reactive beam forming network mayavoid use of absorbing load elements. The use of reactive elementswithout absorbing load elements may enable the radar system to operatemore efficiently. In some examples, the antenna system presented hereinmay be a fully reactive system and not use any absorption components.

Further, the first metal layer may include a first half of the pluralityof wave-radiating channels, where respective wave-radiating channels maybe configured to receive the respective portions of electromagneticwaves from the wave-dividing channels, and where first halves of therespective wave-radiating channels include at least one wave-directingmember configured to propagate sub-portions of electromagnetic waves toanother metal layer.

Moreover, the second metal layer may include second halves of the inputwaveguide channel, the plurality of wave-dividing channels, and theplurality of wave-radiating channels. The second halves of therespective wave-radiating channels may include at least one pair ofoutput ports partially aligned with the at least one wave-directingmember and configured to radiate the sub-portions of electromagneticwaves propagated from the at least one wave-directing member out of thesecond metal layer. More particularly, a combination of a givenwave-directing member with a corresponding pair of output ports may takethe form of (and may be referred to herein as) a DOEWG, as describedabove.

Furthermore, while in this particular example, as well as in otherexamples described herein, the antenna apparatus may be comprised of twometal layers, it should be understood that in still other examples, oneor more of the channels described above may be formed into a singlemetal layer, or into more than two metal layers that make up theantenna. Still further, within examples herein, the concept ofelectromagnetic waves (or portions/sub-portions thereof) propagatingfrom one layer of the antenna architecture to another layer is describedfor the purpose of illustrating functions of certain components of theantenna, such as the wave-directing members. In reality, electromagneticwaves may not be confined to any particular “half” of a channel duringcertain points of their propagation through the antenna. Rather, atthese certain points, the electromagnetic waves may propagate freelythrough both halves of a given channel when the halves are combined toform the given channel.

In some embodiments discussed herein, the two metal layers may be joineddirectly, without the use of adhesives, dielectrics, or other materials,and without methods such as soldering, diffusion bonding, etc. that canbe used to join two metal layers. For example, the two metal layers maybe joined by making the two layers in physical contact without anyfurther means of coupling the layers.

In some examples, the present disclosure provides an integrated powerdivider and method by which each waveguide that feeds a plurality ofradiating doublets of a DOEWG may have its associated amplitudeadjusted. The amplitude may be adjusted based on a pre-defined taperprofile. Additionally, the present DOEWG may be implemented withoutcomplicated manufacturing process. For example, a Computerized NumericalControl (CNC) machining process may be implemented to make theabove-described adjustments in parameters such as height, depth,multiplicity of step-up or step-down phase adjustment components, etc.Yet further, the present disclosure may enable a much more accuratemethod of synthesizing a desired amplitude and phase to cause a realizedgain, sidelobe levels, and beam pointing for the antenna apparatus, ascompared to other types of designs.

The disclosed antenna architecture provides a multi-functional radarcapability. In some examples, the antenna architecture enables at least64 channel MIMO transmission and reception. This MIMO antennaarchitecture may enable diversity in azimuth and elevation to pinpointobjects in the driving scene. In one example, the MIMO antennaarchitecture may provide improvements enable the radar system toidentify bridges and cars on or under bridges. Typical vehicular radarsystems have trouble identify other vehicles near metallic bridges.

The disclosed antenna architecture includes both SAR and MIMOcapabilities that are provided by the 4 SAR transmission antennas, and adedicated SAR reception antenna in combination with a 4 MIMOtransmission antennas and shared uniform linear array.

Referring now to the figures, FIG. 1 illustrates an integrated MIMO andSAR radar antenna architecture. It should be understood that otherlayouts and arrangements of the various elements are possible as well.For examples, it should also be understood that a given application ofsuch an antenna may determine appropriate dimensions and sizes forvarious machined portions of the two metal layers described above (e.g.,channel size, metal layer thickness, etc.) and/or for other machined (ornon-machined) portions/components of the antenna described herein. Forinstance, as discussed above, some example radar systems may beconfigured to operate at an electromagnetic wave frequency of 77 GHz,which corresponds to millimeter electromagnetic wave length. At thisfrequency, the channels, ports, etc. of an apparatus may be of givendimensions appropriated for the 77 GHz frequency. Other example antennasand antenna applications are possible as well.

The radar antenna architecture 100 may be a top view of a split-blockconstruction antenna unit. FIG. 1 shows a view of the top surface of atop block. The top surface of the block contains a plurality of antennaapertures. In the example radar antenna architecture 100, the antennaapertures may be arranged in a plurality of arrays. In various otherexamples, the size, shape, location, and function of the various arraysmay be different than that shown in FIG. 1.

The example radar antenna architecture 100 includes a uniform lineararray 102 for receiving radar signals. The uniform linear array 102 maybe configured as a sixteen by ten array of antenna elements. The exampleradar antenna architecture 100 also includes a SAR reception array 104.The SAR reception array 104 may be configured as a six by ten array ofantenna elements. The example radar antenna architecture 100 alsoincludes four MIMO transmission antenna arrays 106A-106D. Each MIMOarray may be configured as a six by ten array. Further, the exampleradar antenna architecture 100 includes four SAR transmission antennaarrays 108A-108D, each SAR array configured as a six by ten array.

During the operation of the radar system, each MIMO transmission array106A-106D of the example radar antenna architecture 100 may have a beamwidth of approximately 90 degrees and each SAR transmission array108A-108D of the example radar antenna architecture 100 may have a beamwidth of approximately 45 degrees. Both the uniform linear array 102 andthe SAR reception array 104 may have a beam that is electronicallysteerable. In some examples the uniform linear array 102 and the SARreception array 104 may be able to scan their respective beams over22.5, 45, or 90 degrees. In some examples each SAR transmission array108A-108D may be pointed at an angle of 22.5 degrees. Additionally, inan example embodiment, the DOEWG array may have a width of about 148 mmand a length of about 93 mm.

By including the various antenna arrays, the example radar antennaarchitecture 100 may function both in a MIMO and a SAR mode. To operatein a SAR mode, a radar system of the vehicle may transmit and receivemultiple radar pulses. The radar pulses may be transmitted and receivedwhile the vehicle is in motion. Thus, the radar pulses may betransmitted and received from different locations. A SAR radar systemprovides advantages of traditional scanning radar systems due to thetransmitting and receiving being performed at multiple locations. Theradar system may simultaneously (or in parallel) process severalreceived signals. Each received signal may contain information about avariety of radar targets within a field of view of the radar system.Because the signals were transmitted and received from differentlocations, each received signal may contain different information aboutthe variety of radar targets due to the signals being reflected from thetarget objects at different angles relative to the radar unit of thevehicle. By receiving the signals from different angles, the radarsystem may have a higher resolution than traditional scanning radarsystems.

In some examples, the radar system may be configured to interrogate(i.e. transmit radar signals) in a direction normal to the direction oftravel of the vehicle via the SAR radar functionality. Thus, the radarsystem may be able to determine information about roadside object alongwhich the vehicle passes. In some examples, this information may be twodimensional (e.g. distances various objects are from the roadside). Inother examples, this information may be three dimensional (e.g. a pointcloud of various portions of detected objects). Thus, the vehicle may beable to “map” the side of the road as it drives along.

To operate in a MIMO mode, a radar system of the vehicle may transmitand receive multiple radar pulses. The radar pulses may be transmittedand received from a plurality of different antenna apertures (e.g.antenna arrays). The term MIMO comes from a radar system having multipleinputs and multiple outputs. It may be desirable for each of themultiple input antennas and each of the multiple output antennas tooperate uncoupled (that is receive a separate diverse signal) from eachother respective input and output antenna. A radar may have MIMOcapabilities in multiple ways. First, spatial diversity (i.e. adifference between physical location) of radar transmitters (and/orreceivers) may enable MIMO functionality. Second, coding diversity mayenable a radar system to transmit a signal that has a respective coding.The coding may include multiple signals that are orthogonal to eachother so virtual diverse channels can be created. In some system, acombination of spatial diversity and coding diversity may be used toestablish the MIMO diversity. Yet, additionally, time division multipleaccess (TDMA) can provide time diversity to allow multiple transmissionand reception antennas to be used. Also, in other examples, a frequencydivision multiple access (FDMA) may also be used for diversity.

FIG. 2 illustrates another view of an integrated MIMO and SAR radarantenna architecture 200. FIG. 2 shows a three dimensional view of thesplit-block assembly. Similar to FIG. 1, the top surface of the blockcontains a plurality of antenna apertures. In the example radar antennaarchitecture 200, the antenna apertures may be arranged in a pluralityof arrays. In various other examples, the size, shape, location, andfunction of the various arrays may be different than that shown in FIG.2.

Again, similar to FIG. 1, the example radar antenna architecture 200includes a uniform linear array 202 for receiving radar signals. Theuniform linear array 202 may be configured as a sixteen by ten array ofantenna elements. The uniform linear array 202 may be configured toreceive radar signals when the radar unit is operating in either the SARor the MIMO mode. The example radar antenna architecture 200 alsoincludes a SAR reception array 204. The SAR reception array 204 may beconfigured as a six by ten array of antenna elements. The example radarantenna architecture 200 also includes four MIMO transmission antennaarrays and four SAR transmission antenna arrays located in thetransmission section 206. Each transmission array may be configured as asix by ten array.

The radar antenna architecture 200 also shows the seam 208. The seam 208is a position where the top portion of the split-block assembly and thebottom portion of the split-block assembly come together to form a seam.

FIG. 3 illustrates an expanded view of an integrated MIMO and SAR radarantenna architecture 300. As shown in FIG. 3, a top portion 302 and abottom portion 304 of the split-block assembly are separated. And, shownas dotted lines in both the top portion 302 and the bottom portion 304are a series of waveguides 306. The waveguides 306 couple the radiatingelements to coupling structures outside of the radar antennaarchitecture 300. The coupling structures are configured to eitherinject electromagnetic energy into the radar antenna architecture 300for transmission by the antennas of the arrays or remove electromagneticenergy from the radar antenna architecture 300 received by the antennasof the arrays. In some examples, a portion of each waveguide lies inboth the top portion 302 and the bottom portion 304. In this example,when the top portion 302 and the bottom portion 304 are coupledtogether, the waveguide is formed. The waveguides 306 will be discussedfurther with respect to other figures.

FIG. 4 illustrates an internal view of an integrated MIMO and SAR radarantenna architecture 400. The radar antenna architecture 400 shows anexample layout of ports, waveguides, and radiating structures for usewith the disclosed radar systems. The waveguides of FIGS. 3 and 4 may beconfigured to perform both power splitting and beamforming. The powersplitting and beam forming may be provided by the waveguides based onthe description of the waveguides in the remaining figures.

Some components illustrated in of FIGS. 5A, 5B, and 5E are shown usingbroken lines, including elongated segments 504, second end 510, andpower dividers 514. The components shown in broken lines are describedherein with respect to the alignments shown in the respective figures.However, these components may have altered geometries and/or locationswithin the context of the disclosure. For example, the presentlydiscussed waveguide dividing networks as disclosed herein may replace aportion of the broken line components of FIGS. 5A, 5B, and 5E. Further,the geometries of the waveguides of FIG. 5A-E are for explanationpurposes of the waveguides functionality.

FIG. 5A illustrates an example first metal layer 500 including a firsthalf of a plurality of waveguide channels 502. These waveguide channels502 may comprise multiple elongated segments 504. At a first end 506 ofeach elongated segment 504 may be a plurality of collinearwave-directing members 508, each with sizes similar or different fromother wave-directing members. In line with the description above, thefirst ends 506 of the elongated segments 504 may be referred to hereinas a first half of wave-radiating channels.

At a second end 510 of the channels 502 opposite the first end 506, oneof the elongated segments 504 may include a through-hole 512 (i.e.,input port). A given amount of power may be used to feed a correspondingamount of electromagnetic waves (i.e., energy) into the apparatus, andthe through-hole 512 may be the location where these waves are fed intothe apparatus. In line with the description above, the singlechannel/segment of the waveguide channels 502 that includes the inputport may be referred to herein as an input waveguide channel.

Upon entering the apparatus, the electromagnetic waves may generallytravel in the +x direction, as shown, towards an array of power dividers514 (i.e., a “beam-forming network”). The array 514 may function todivide up the electromagnetic waves and propagate respective portions ofthe waves to respective first ends 506 of each elongated segment 504.More specifically, the waves may continue to propagate in the +xdirection after leaving the array 514 toward the wave-directing members508. In line with the description above, the array 514 section of thewaveguide channels may be referred to herein as wave-dividing channels.

As the portions of the electromagnetic waves reach the wave-directingmembers 508 at the first end 506 of each elongated segment 504 of thewaveguide channels 502, the wave-directing members 508 may propagatethrough respective sub-portions of the electromagnetic energy to asecond half of the waveguide channels (i.e., in the +z direction, asshown). For instance, the electromagnetic energy may first reach awave-directing member that is recessed, or machined further into thefirst metal layer 500 (i.e., a pocket). That recessed member may beconfigured to propagate a smaller fraction of the electromagnetic energythan each of the subsequent members further down the first end 506,which may be protruding members rather than recessed members. Further,each subsequent member may be configured to propagate a greater fractionof the electromagnetic waves travelling down that particular elongatedsegment 504 at the first end 506 than the member that came before it. Assuch, the member at the far end of the first end 506 may be configuredto propagate the highest fraction of electromagnetic waves. Eachwave-directing member 508 may take various shapes with variousdimensions. In other examples, more than one member (or none of themembers) may be recessed. Still other examples are possible as well. Inaddition, varying quantities of elongated segments are possible.

A second metal layer may contain a second half of the one or morewaveguide channels, where respective portions of the second half of theone or more waveguide channels include an elongated segmentsubstantially aligned with the elongated segment of the first half ofthe one or more waveguide channels and, at an end of the elongatedsegment, at least one pair of through-holes partially aligned with theat least one wave-directing member and configured to radiateelectromagnetic waves propagated from the at least one wave-directingmember out of the second metal layer.

Within examples, the elongated segment of the second half may beconsidered to substantially align with the elongated segment of thefirst half when the two segments are within a threshold distance, orwhen centers of the segments are within a threshold distance. Forinstance, if the centers of the two segments are within about ±0.051 mmof each other, the segment may be considered to be substantiallyaligned.

In another example, when the two halves are combined (i.e., when the twometal layers are joined together), edges of the segments may beconsidered to be substantially aligned if an edge of the first half of asegment and a corresponding edge of the second half of the segment arewithin about ±0.051 mm of each other.

In still other examples, when joining the two metal layers, one layermay be angled with respect to the other layer such that their sides arenot flush with one another. In such other examples, the two metallayers, and thus the two halves of the segments, may be considered to besubstantially aligned when this angle offset is less than about 0.5degrees.

In some embodiments, the at least one pair of through-holes may beperpendicular to the elongated segments of the second half of the one ormore waveguide channels. Further, respective pairs of the at least onepair of through-holes may include a first portion and a second portion.As such, a given pair of through-holes may meet at the first portion toform a single channel. That single channel may be configured to receiveat least the portion of electromagnetic waves that was propagated by acorresponding wave-directing member and propagate at least a portion ofelectromagnetic waves to the second portion. Still further, the secondportion may include two output ports configured as a doublet and may beconfigured to receive at least the portion of electromagnetic waves fromthe first portion of the pair of through-holes and propagate at leastthat portion of electromagnetic waves out of the two output ports.

FIG. 5B illustrates the second metal layer 520 described above. Thesecond metal layer 520 may include a second half of the plurality ofwaveguide channels 502 of the first metal layer 500 shown in FIG. 5A(i.e., a second half of the input waveguide channel, the wave-dividingchannels, and the wave-radiating channels). As shown, the second half ofthe waveguide channels 502 may take on the general form of the firsthalf of the channels, so as to facilitate proper alignment of the twohalves of the channels. The elongated segments of the second half 522may include second halves of the array of power dividers 524. Asdescribed above, electromagnetic waves may travel through the array 524,where they are divided into portions, and the portions then travel(i.e., in the +x direction, as shown) to respective ends 526 of thesecond halves of the elongated segments 522. Further, an end 526 of agiven elongated segment may include multiple pairs of through-holes 528,which may be at least partially aligned with the wave-directing members508 of the first metal layer 500. More specifically, each pair ofthrough-holes may be at least partially aligned with a correspondingwave-directing member, also referred to as a reflecting element, suchthat when a given sub-portion of electromagnetic waves are propagatedfrom the first metal layer 500 to the second metal layer 520, asdescribed above, those sub-portions are then radiated out of the pair ofthrough-holes (i.e., a pair of output ports) in the −z direction, asshown. Again, the combination of a given wave-directing member and acorresponding pair of output ports may form a DOEWG, as described above.

Moreover, a combination of all the DOEWGs may be referred to herein as aDOEWG array. In antenna theory, when an antenna has a larger radiatingaperture (i.e., how much surface area of the antenna radiates, where thesurface area includes the DOEWG array) that antenna may have higher gain(dB) and a narrower beam width. As such, in some embodiments, ahigher-gain antenna may include more channels (i.e., elongatedsegments), with more DOEWGs per channel. While the example antennaillustrated in FIGS. 5A and 5B may be suitable for autonomous-vehiclepurposes (e.g., six elongated segments, with five DOEWGs per segment),other embodiments may be possible as well, and such other embodimentsmay be designed/machined for various applications, including, but notlimited to, automotive radar.

For instance, in such other embodiments, an antenna may include aminimum of a single DOEWG. With this arrangement, the output ports mayradiate energy in all directions (i.e. low gain, wide beamwidth).Generally, an upper limit of segments/DOEWGs may be determined by a typeof metal used for the first and second metal layers. For example, metalthat has a high resistance may attenuate an electromagnetic wave as thatwave travels down a waveguide channel. As such, when a larger,highly-resistive antenna is designed (e.g., more channels, moresegments, more DOEWGs, etc.), energy that is injected into the antennavia the input port may be attenuated to an extent where not much energyis radiated out of the antenna. Therefore, in order to design a largerantenna, less resistive (and more conductive) metals may be used for thefirst and second metal layers. For instance, in embodiments describedherein, at least one of the first and second metal layers may bealuminum. Further, in other embodiments, at least one of the first andsecond metal layers may be copper, silver, or another conductivematerial. Further, aluminum metal layers may be plated with copper,silver, or other low-resistance/high-conductivity materials to increaseantenna performance. Other examples are possible as well.

The antenna may include at least one fastener configured to join thefirst metal layer to the second metal layer so as to align the firsthalf of the one or more waveguide channels with the second half of theone or more waveguide channels to form the one or more waveguidechannels (i.e., align the first half of the plurality of wave-dividingchannels with the second half of the plurality of wave-dividingchannels, and align the first half of the plurality of wave-radiatingchannels with the second half of the plurality of wave-radiatingchannels). To facilitate this in some embodiments, the first metallayer, a first plurality of through-holes (not shown in FIG. 5A) may beconfigured to house the at least one fastener. Additionally, in thesecond metal layer, a second plurality of through-holes (not shown inFIG. 5B) may be substantially aligned with the first plurality ofthrough-holes and configured to house the at least one fastener forjoining the second metal layer to the first metal layer. In suchembodiments, the at least one fastener may be provided into the alignedfirst and second pluralities of through-holes and secured in a mannersuch that the two metal layers are joined together.

In some examples, the at least one fastener may be multiple fasteners.Mechanical fasteners (and technology used to facilitate fastening) suchas screws and alignment pins may be used to join (e.g., screw) the twometal layers together. Further, in some examples, the two metal layersmay be joined directly to each other, with no adhesive layer in between.Still further, the two metal layers may be joined together using methodsdifferent than adhesion, such as diffusion bonding, soldering, brazing,and the like. However, it is possible that, in other examples, suchmethods may be used in addition to or alternative to any methods forjoining metal layers that are known or not yet known.

In some embodiments, one or more blind-holes may be formed into thefirst metal layer and/or into the second metal layer in addition to oralternative to the plurality of through-holes of the first and/or thesecond metal layer. In such embodiments, the one or more blind-holes maybe used for fastening (e.g., housing screws or alignment pins) or may beused for other purposes.

FIG. 5C illustrates an assembled view of an example antenna 540. Theexample antenna 540 may include the first metal layer 500 and the secondmetal layer 520. The second metal layer 520 may include a plurality ofholes 542 (through-holes and/or blind-holes) configured to housealignment pins, screws, and the like. The first metal layer 500 mayinclude a plurality of holes as well (not shown) that are aligned withthe holes 542 of the second metal layer 520. The two metal layers mayjoin at a common plane 530.

Further, FIG. 5C illustrates a DOEWG array 544 of a given width 546 anda given length 548, which may vary based on the number of DOEWGs andchannels of the antenna 540. Further, in such an example embodiment,these dimensions, in addition to or alternative to other dimensions ofthe example antenna 540, may be machined with no less than about a 0.51mm error, though in other embodiments, more or less of an error may berequired. Other dimensions of the DOEWG array are possible as well.

In some embodiments, the first and second metal layers 500, 520 may bemachined from aluminum plates (e.g., about 6.35 mm stock). In suchembodiments, the first metal layer 500 may be at least 3 mm in thickness(e.g., about 5.84 mm to 6.86 mm). Further, the second metal layer 520may be machined from a 6.35 mm stock to a thickness of about 3.886 mm.Other thicknesses are possible as well.

In some embodiments, the joining of the two metal layers 500, 520 mayresult in an air gap or other discontinuity between mating surfaces ofthe two layers. In such embodiments, this gap or continuity should beproximate to (or perhaps as close as possible to) a center of the lengthof the antenna apparatus and may have a size of about 0.05 mm orsmaller.

FIG. 5D illustrates another assembled view of the example antenna 540.As shown, the first metal layer 500 may include a plurality of holes 550(through-holes and/or blind-holes) configured to house alignment pins,screws, and the like. One or more of the plurality of holes 550 may bealigned with the holes 542 of the second metal layer 520. Further, FIG.5D shows the input port 512, where the antenna 540 may receiveelectromagnetic waves into the one or more waveguide channels 502. Thetwo metal layers may join at a common plane 530.

FIG. 5E illustrates conceptual waveguide channels 560 formed inside anassembled example antenna. More particularly, the waveguide channels 560take the form of the waveguide channels 502 of FIGS. 5A and 5B. Forinstance, the channels 560 include an input port 562 to the inputwaveguide channel 564. The channels 560 also include wave-dividingchannels 566 and a plurality of radiating doublets 568 (i.e., a DOEWGarray). As described above, when electromagnetic waves enter thechannels 560 at the input port 562, they may travel in the +x directionthrough the input waveguide channel 564 and be divided into portions bythe wave-dividing channels 566 (e.g., by the power dividers). Thoseportions of electromagnetic waves may then travel in the +x direction torespective radiating doublets 568, where sub-portions of those portionsare radiated out each DOEWG through pairs of output ports, such as pair570, for instance.

In a particular wave-radiating channel, a portion of electromagneticwaves may first be propagated through a first DOEWG with a recessedwave-directing member 572 (i.e., an inverse step, or “well”), asdiscussed above. This recessed wave-directing member 572 may beconfigured to radiate the smallest fraction of energy of all the membersof the DOEWGs of the particular wave-radiating channel. In someexamples, subsequent wave-directing members 574 may be formed (e.g.,protruded, rather than recessed) such that each subsequent DOEWG canradiate a higher fraction of the remaining energy than the DOEWG thatcame before it. Phrased another way, each wave-directing member 572, 574may generally be formed as a “step cut” into a horizontal (+x direction)channel (i.e., a wave-radiating channel, or the “first end” of an“elongated segment” as noted above) and used by the antenna to tune theamount of energy that is radiated vs. the amount of energy that istransmitted further down the antenna.

In some embodiments, a given DOEWG may not be able to radiate more thana threshold level of energy and may not be able to radiate less than athreshold level of energy. These thresholds may vary based on thedimensions of the DOEWG components (e.g., the wave-directing member, ahorizontal channel, a vertical channel, a bridge between the two outputports, etc.), or may vary based on other factors associated with theantenna.

In some embodiments, the first and second metal layers may be machinedsuch that various sides of the waveguide channels 560 have roundededges, such as edge 576, 578, and 580, for example. Further shown inFIG. 5E are both attenuation ports 582 and attenuation components 584.The attenuation components 584 may be coupled to the attenuation ports582. And the attenuation ports 582 may be coupled to the elongatedsegments 522 of the wave-dividing channels 566. The design of theattenuation components 584 and attenuation ports 582 are discussedfurther with respect to FIG. 6B. In examples, where the beamforming(i.e. dividing network) is not completely reactive the attenuation ports582 may be used to removed electromagnetic energy from the waveguides.The attenuation ports 582 may couple electromagnetic energy toattenuation components 584 in order to absorb the undesiredelectromagnetic energy. Additionally, the dashed line 588 indicates thecommon plane of the feed waveguides.

FIG. 6A illustrates a network of wave-dividing channels 600 of anexample antenna, in accordance with an example embodiment. And FIG. 6Billustrates an alternate view of the network of wave-dividing channels600, in accordance with an example embodiment.

In some embodiments, the network (e.g., beam-forming network, as notedabove) of wave-dividing channels 600 may take the form of a tree ofpower dividers, as shown in FIG. 6A. Energy may enter the antennathrough the input waveguide channel and is divided (i.e., split) intosmaller portions of energy at each power divider, such as power divider602, and may be divided multiple times via subsequent power dividers sothat a respective amount of energy is fed into each of thewave-radiating channels (energy A-F, as shown). The amount of energythat is divided at a given power divider may be controlled by a powerdivision ratio (i.e., how much energy goes into one channel 604 versushow much energy goes into another channel 606 after the division). Agiven power division ratio may be adjusted based on the dimensions ofthe corresponding power divider. Further, each power divider andassociated power division ratio may be designed/calculated in order toachieve a desired “power taper” at the wave-radiating channels. In sucha case, the antenna may be designed with a “Taylor window” (e.g.,radiation ripples drop off at edges) or other window such that sidelobesof the antenna's far-field radiation pattern may be low. As an example,the power division ratios of the power dividers may be set such thatenergy portions A, B, C, D, E, and F are approximately 3.2%, 15.1%,31.7%, 31.7%, 15.1%, 3.2% of the energy, respectively. Other examplepower divisions are possible as well.

Within examples, a technique for dividing energy between two channels604, 606 may be to use a structure of channels (e.g., a four-portbranchline coupler) such as that shown at the bottom of FIG. 6A. Such atechnique and structure design may include a “terminator” 608 at the endof a channel, as shown in FIGS. 6A and 6B, where small wedges of radiofrequency-absorbing material may be located to absorb energy thatreturns backwards through the channel to that terminator 608. Theterminator may also be the absorption component of FIG. 5E.

FIG. 7A illustrates an example wave-radiating doublet of an exampleantenna, in accordance with an example embodiment. More specifically,FIG. 7A illustrates a cross-section of an example DOEWG 700. As notedabove, a DOEWG 700 may include a horizontal feed (i.e., channel), avertical feed (i.e. a doublet neck), and a wave-directing member 704.The vertical feed may configured to couple energy from the horizontalfeed to two output ports 702, each of which is configured to radiate atleast a portion of electromagnetic waves out of the DOEWG 700. In someembodiments, the farthest DOEWG from the input port may include abackstop at location 706. DOEWGs that come before the last DOEWG maysimply be open at location 706 and electromagnetic waves may propagatethrough that location 706 to subsequent DOEWGs. For example, a pluralityof DOEWGs may be connected in series where the horizontal feed is commonacross the plurality of DOEWGs (as shown in FIG. 7B). FIG. 7A showsvarious parameters that may be adjusted to tune the amplitude and/orphase of an electromagnetic signal that couples into the radiatingelement.

In order to tune a DOEWG such as DOEWG 700, the vertical feed width,vfeed_a, and various dimensions of the step 704 (e.g., dw, dx, and dz1)may be tuned to achieve different fractions of radiated energy out theDOEWG 700. The step 704 may also be referred to as a reflectingcomponent as it reflects a portion of the electromagnetic waves thatpropagate down the horizontal feed into the vertical feed. Further, insome examples, the height dz1 of the reflecting component may benegative, that is may extend below the bottom of the horizontal feed.Similar tuning mechanisms may be used to tune the offset feed as well.For example, the offset feed may include any of the vertical feed width,vfeed_a, and various dimensions of the step (e.g., dw, dx, and dz1) asdiscussed with respect to the radiating element.

In some examples, each output port 702 of the DOEWG 700 may have anassociated phase and amplitude. In order to achieve the desired phaseand amplitude for each output port 702, various geometry components maybe adjusted. As previously discussed, the step (reflecting component)704 may direct a portion of the electromagnetic wave through thevertical feed. In order to adjust an amplitude associated with eachoutput port 702 of a respective DOEWG 700, a height associated with eachoutput port 702 may be adjusted. Further, the height associated witheach output port 702 could be the height or the depths of this feedsection of output port 702, and not only could be a height or depthadjustment but it could be a multiplicity of these changes or steps orascending or descending heights or depths in general.

As shown in FIG. 7A, height dz2 and height dz3 may be adjusted tocontrol the amplitude with respect to the two output ports 702. Theadjustments to height dz2 and height dz3 may alter the physicaldimensions of the doublet neck (e.g. vertical feed of FIG. 7A). Thedoublet neck may have dimensions based on the height dz2 and height dz3.Thus, as the height dz2 and height dz3 are altered for various doublets,the dimensions of the doublet neck (i.e. the height of at least one sideof the doublet neck) may change. In one example, because height dz2 isgreater than height dz3, the output port 702 associated with (i.e.located adjacent to) height dz2 may radiate with a greater amplitudethan the amplitude of the signal radiated by the output port 702associated with height dz3.

Further, in order to adjust the phase associated with each output port702, a step 710A and 710B may be introduced for each output port 702.The step 710A and 710B in the height may cause a phase of a signalradiated by the output port 702 associated with the step to change.Thus, by controlling both the height and the step 710A and 710Bassociated with each output port 702, both the amplitude and the phaseof a signal transmitted by the output port 702 may be controlled. Invarious examples, the step 710A and 710B may take various forms, such asa combination of up-steps and down-steps. Additionally, the number ofsteps 710A and 710B may be increased or decreased to control the phase.

The above-mentioned adjustments to the geometry may also be used toadjust a geometry of the offset feed where it connects to the waveguide.For example, heights, widths, and steps may be adjusted or added to theoffset feed in order to adjust the radiation properties of the system.An impedance match, phase control, and/or amplitude control may beimplemented by adjusting the geometry of the offset feed.

FIG. 7B illustrates an example offset feed waveguide portion 756 of anexample antenna, in accordance with an example embodiment. As shown inFIG. 7B, a waveguide 754 may includes a plurality of radiating elements(shown as 752A-752E) and an offset feed 756. Although the plurality ofradiating elements are shown as doublets in FIG. 7B, other radiatingstructures may be use as well. For example, singlets, and any otherradiating structure that can be coupled to a waveguide may be used aswell.

The waveguide 754 may be configured in a similar manner to thosewaveguides discussed throughout this disclosure. For example, thewaveguide 754 may include various shapes and structures configured todirect electromagnetic power to the various radiating elements 752A-E ofwaveguide 754. As discussed with respect to FIG. 5E, a portion ofelectromagnetic waves propagating through waveguide 754 may be dividedand directed by various recessed wave-directing member (572 of FIG. 5E)and raised wave-directing members (574 of FIG. 5E). The pattern ofwave-directing members shown in FIG. 7B is one example for thewave-directing members. Based on the specific implementation, thewave-directing members may have different sizes, shapes, and locations.Additionally, the waveguide may be designed to have the waveguide ends760A and 760B to be tuned shorts. For example, the geometry of the endsof the waveguides may be adjusted so the waveguide ends 760A and 760Bact as tuned shorts.

At each junction of a respective radiating elements 752A-E of waveguide754, the junction may be considered a two-way power divider. Apercentage of the electromagnetic power may couple into the neck of therespective radiating elements 752A-E and the remaining electromagneticpower may continue to propagate down the waveguide. By adjusting thevarious parameters (e.g. neck width, heights, and steps) of eachrespective radiating element 752A-E, the respective percentage of theelectromagnetic power may be controlled. Thus, the geometry of eachrespective radiating element 752A-E may be controlled in order toachieve the desired power taper. Thus, by adjusting the geometry of eachof the offset feed and the each respective radiating element 752A-E, thedesired power taper for a respective waveguide and its associatedradiating elements may be achieved.

Electromagnetic energy may be injected into the waveguide 754 via thewaveguide feed 756. The waveguide feed 756 may be a port (i.e. a throughhole) in a bottom metal layer, such as layer 304 of FIG. 3. Anelectromagnetic signal may be coupled from outside the antenna unit intothe waveguide 754 through the waveguide feed 756. The electromagneticsignal may come from a component located outside the antenna unit, suchas a printed circuit board, another waveguide, or other signal source.In some examples, the waveguide feed 756 may be coupled to anotherdividing network of waveguides (such as or similar to the dividingnetworks described with respect to FIGS. 5A, 5B, and 5E).

In some additional examples, the various radiating elements 752A-E maybe configured to receive electromagnetic energy. In these examples, thewaveguide feed 756 may be used to remove electromagnetic energy from thewaveguide 754. When electromagnetic energy is removed from the waveguide754, it may be coupled into components for further processing.

In many traditional examples, a waveguide feed is located at the end ofa waveguide. In the example shown in FIG. 7B, the waveguide feed 756 islocated at an offset position from the ends of the waveguide betweenradiating elements 752A and 752B. By locating the waveguide feed 756 atan offset position, the electromagnetic energy that couples into thewaveguide 754 may be divided more easily. Further, by locating thewaveguide feed 756 at an offset position, an antenna unit may bedesigned in a more compact manner.

When electromagnetic energy enters waveguide 754, it will be split inorder to achieve a desired radiation pattern. For example, it may bedesirable for each of a series of radiating elements 752A-E to receive apredetermined percentage of the electromagnetic energy from thewaveguide 754. The waveguide may include a power dividing element 758that is configured to split the electromagnetic energy the travels downeach side of the waveguide. In some examples, the power dividing element758 may cause the power to be divided evenly or unevenly. The radiatingelements 752A-E are configured to radiate the electromagnetic energythey receive. In some examples, each radiating element 752A-E mayreceive approximately the same percentage of the electromagnetic energyas each other radiating element 752A-E. In other examples, eachradiating element 752A-E may receive a percentage of the electromagneticenergy based on a taper profile.

In some example taper profiles, radiating elements 752A-E located closerto the center of waveguide 754 may receive a higher percentage of theelectromagnetic energy. If electromagnetic energy is injected into theend of the waveguide 754, it may be more difficult to design thewaveguide 754 to correctly split power between the various radiatingelements 752A-E. By locating the waveguide feed 756 at an offsetposition, a more natural power division between the various radiatingelements 752A-E may be achieved. The offset position for the waveguidefeed 756 may be any position along the waveguide 754 where the waveguidefeed 756 is location corresponding to a position at or between some ofthe radiating elements.

In one example, the waveguide 754 may have 10 radiating elements and thewaveguide feed 756 may be located in at a position with 5 radiatingelements on each side of the waveguide feed 756. The radiating elementsmay have an associated taper profile that specifies the radiatingelements in the center should receive a higher percentage of theelectromagnetic energy than the other elements. Because the waveguidefeed 756 is located closer to the center elements, it is more natural todivide power with elements closest to the waveguide feed 756 receivinghigher power. Further, if the waveguide 754 has the waveguide feed 756located at the center of the waveguide 754, the waveguide 754 may bedesigned in a symmetrical manner to achieve the desired power division.In examples where the waveguide feed 756 is located away from the centerof the radiating elements, the waveguide 754 may be designed to splitthe power in an uneven (i.e. non-symmetric) manner.

In some examples, the present system may operate in one of two modes. Inthe first mode, the system may receive electromagnetic energy from asource for transmission (i.e. the system may operate as a transmissionantenna). In the second mode, the system may receive electromagneticenergy from outside of the system for processing (i.e. the system mayoperate as a reception antenna). In the first mode, the system mayreceive electromagnetic energy at a waveguide feed, divide theelectromagnetic energy for transmission by a plurality of radiatingelements, and radiate the divided electromagnetic energy by theradiating elements. In the second mode, the system may receiveelectromagnetic energy at the plurality of radiating elements, combinethe received electromagnetic energy, and couple the combinedelectromagnetic energy out of system for further processing.

It should be understood that other shapes and dimensions of thewaveguide channels, portions of the waveguide channels, sides of thewaveguide channels, wave-directing members, and the like are possible aswell. In some embodiments, a rectangular shape of waveguide channels maybe highly convenient to manufacture, though other methods known or notyet known may be implemented to manufacture waveguide channels withequal or even greater convenience.

FIG. 7C illustrates an example waveguide 772 termination comprisingcoupling port 774, attenuation components 780, and the couplingcomponent 778. The attenuation components 780 may be mounted on a PCB776 (e.g. the attenuation components 780 may be metallic traces on aPCB). The PCB may be mounted to a bottom surface of an antenna like thatshown in FIG. 5D. Furthermore, FIG. 7C illustrates one example use of acoupling port 774. The coupling port 774 may also be used in instancesother than the presently disclosed antenna apparatus. For example, thecoupling port 774 may be used in any instance where an electromagneticsignal is being coupled into and/or out of a waveguide. Further, thecoupling port 774 as disclosed herein may also be used to efficientlycouple a signal from a PCB to a radiating structure, like an antenna,without the use of the waveguide beamforming network.

Although FIG. 7C is shown with the coupling component 778 as adifferential pair connected to attenuation components 780, in otherexamples, the coupling component 778 may be a different shape, such as asingle patch. Additionally, the coupling component 778 may be abidirectional component that may be able to both feed an electromagneticsignal for transmission by the antenna unit and couple anelectromagnetic signal from the waveguide to an attenuation component.

The waveguide 772 of FIG. 7C may be a portion of a waveguide elongatedsegments, such as elongated segments 504 of FIG. 5A. More specifically,the waveguide 772 of FIG. 7C may be one of the elongated segments thatdoes not include the feed. As previously discussed, during the operationof the antenna some electromagnetic energy that is not radiated by theradiation components may be reflected back into the waveguide. In orderto remove the reflected electromagnetic energy, the waveguide 772 may becoupled to a coupling port 774. The coupling port 774 may be alignedperpendicularly, and out of the plane of the waveguide 772. The couplingport 774 may be configured to couple the reflected electromagneticenergy to an attenuation component (shown here as lines 780) located ona PCB 776 by way of a coupling component 778.

In some examples, such as shown in FIG. 7C, each coupling port 774 maybe shaped in a way to match (or approximately match) an impedance of thewaveguide. By impedance matching, the amount of the reflectedelectromagnetic energy that is coupled from the waveguide 772 to thecoupling port 774 may be maximized. For example, the coupling port 774may have portions that are of different dimensions to achieve thecorrect impedance matching. Further, in instances where an antenna unithas multiple coupling ports, each coupling port may have its owndimensions based on the impedance match desired for each respectivecoupling port.

The coupling port 774 is shown having a neck 782 that has a narrowerdimension than the rest of the coupling port 774. In this example bynarrowing the neck 782 the inductance of the coupling port 774 isincreased. The increase in inductance may be used to match (or moreapproximately match) the impedance of the coupling component 778 withthe impedance of the waveguide 772. When the impedance is matched, thepower transfer of the electromagnetic energy between the waveguide 772and the coupling component 778 may be maximized. A widening of the widthof the coupling port 774 may increase the capacitance of coupling port774. Depending on the specific embodiment, the dimensions of thecoupling port 774 may be designed for an impedance match between thewaveguide 772 and the coupling component 778.

Additionally, the coupling port 774 and coupling component 778 are showncoupling to the bottom of the waveguide. In other examples, thealignment of the coupling port 774, PCB 776, and coupling component 778may have a different alignment. For example, the coupling may be to aside or end of a waveguide as well (i.e. coupled orthogonally to thedirection of the plane of the waveguide layer).

To create the coupling port 774, the coupling port 774 may be machinedfrom both the top side of the coupling port 774 and the bottom side ofthe coupling port 774. By designing a coupling port 774 that hasdimensions that can be machined from both sides, a coupling port 774 maybe created that performs the impedance matching function while alsobeing relatively simple to manufacture. More complex versions of thecoupling port may be designed as well, but having a port that may bemachined from both the top and bottom side of the coupling port maydecrease machining complexity.

As previously discussed, the coupling component 778 is configured tocouple at least a portion of the reflected electromagnetic energy fromthe waveguide to the attenuation component 780 through the coupling port774. In this way, when the coupling component 778 couples the at least aportion of the reflected electromagnetic energy, the coupling component778 may essentially act as a receiving antenna. The coupling component778 receives the at least a portion of the reflected electromagneticenergy from the waveguide and couples it through the coupling port.

In other examples, the coupling port 774 may function to injectelectromagnetic energy into the waveguide. In this example, component778 is configured to couple at least a portion of the electromagneticenergy from feed traces (not shown) on the PCB 776 to the waveguide 772through the coupling port 774. In this way, when the coupling component778 couples the at least a portion of the electromagnetic energy, thecoupling component 778 may essentially act as a transmitting antenna.The coupling component 778 transmits at least a portion of theelectromagnetic energy from the feed traces and couples it through thecoupling port.

In various different examples, the coupling component 778 may takedifferent forms. For example, the coupling component 778 may be ametallic loop-shaped structure, as shown in FIG. 7C. The couplingcomponent 778 may function similarly to an antenna, that is the couplingcomponent 778 may be able to transmit or receive electromagnetic energy(i.e. a wave). Functionally, in one example, the coupling component 778may be a component configured to convert a guided wave from a waveguideto a guided wave outside of the waveguide (e.g. couple the wave to anattenuation component). In another example, the coupling component 778may be a component configured to convert a guided wave from outside thewaveguide to a guided wave in a waveguide.

In various examples, the coupling component 778 may be made in variousways and with various materials. The coupling component may be ametallic trace (or patch) on the circuit board 776. However, in otherexamples, the coupling component may be a discrete component attached tothe PCB. For example, the coupling component may be formed of a ceramicthat is coated, plated, or otherwise overlaid with metal. The couplingcomponent 778 may also be formed from stamped metal, bent metal, orother another metal structure. In some additional examples, the couplingcomponent 778 may itself be a metallic strip or component on a secondcircuit board that may be surface mounted to PCB 776.

Therefore, there are many structures that can function to cause theconversion of the wave from a wave in the waveguide to a wave not in thewaveguide and can take the place of coupling component 778.

In some examples, the coupling component 778 may be a bi-directionalcoupler that functions to both (i) couple a signal from outside thewaveguide into the waveguide and (ii) couple signal from inside thewaveguide out of the waveguide.

In some further examples, the coupling component 778 may be configuredto couple a differential mode signal from outside the waveguide into thewaveguide. In some additional examples, the coupling component 778 maybe configured to couple signal from inside the waveguide out of thewaveguide as a differential mode signal.

In some additional examples, the coupling component 778 may beconfigured to couple a single mode signal from outside the waveguideinto the waveguide. In some additional examples, the coupling component778 may be configured to couple signal from inside the waveguide out ofthe waveguide as a single mode signal.

In various embodiments, the coupling component 778 may be designed tohave an impedance that optimizes the percentage of electromagneticenergy that the coupling component 778 couples between its input andoutput.

FIG. 8A illustrates an example two-dimensional beamforming network, inaccordance with an example embodiment. The two-dimensional beamformingnetwork has two main components. The two-dimensional beamforming networkincludes a waveguide input 802, a power dividing section 804, and aphase adjusting section 806. The two-dimensional beamforming network maybe located in the same plane of the split-block assembly as the feedwaveguides.

The two-dimensional beamforming network of FIG. 8A may include onlyreactive components. As previously discussed, the use of reactivecomponents may eliminate the need for beamforming network to includeabsorption components that were previously discussed.

The two-dimensional beamforming network may receive electromagneticenergy at the waveguide input 802, ends 808A-808D may be shorts. Thereceived electromagnetic energy may be divided by the power dividingsection 804. The power dividing section 804 may divide theelectromagnetic energy as divided electromagnetic energy based on apredetermined taper profile. The divided electromagnetic energy may haveits phase adjusted by the phase adjusting section 806. The phaseadjustment provided by of each respective phase adjusting trombonessections (806A-806F) in splitting section 806 may also be defined basedon the taper profile. As shown in FIG. 8A, a portion of the waveguidesof the phase adjusting section 806 may have a width that is differentthan the widths of the feed waveguides. Further, the waveguides of phaseadjusting section 806 may be folded so each respective phase adjustingsection 806 occupies the same physical length in the x direction.

The power dividing elements of FIG. 8A are a two-dimensional dividingnetwork of waveguides. The two-dimensional dividing network ofwaveguides use waveguide geometry to divide power with no changes to thethickness of the waveguide A dimension. As previously discussed, thefeed waveguides may have a predetermined height and width. Thepredetermined height and width may be based on a frequency of operationof radar unit. The two-dimensional dividing network may includewaveguides 806A-806F that differ in width from the predetermined width(i.e. the N dimension) of the feed waveguides in order to achieve thedesired taper profile. By adjusting the waveguide widths, both the phaseand amplitude of the splitting of the electromagnetic energy may becontrolled. Thus, the dividing network may have a geometry that isvaried compared to the feed waveguide geometry.

In the present disclosure, the feed waveguides may be divided betweenthe top and bottom portions of the split-block assembly. Further, thefeed waveguides and the two-dimensional dividing network may all belocated in a common plane 810 where the midpoint of the height of feedwaveguides is common for all of the feed waveguides. When the two blockpieces are brought together, the two half-height waveguide portions maycouple and form a full-height waveguide.

FIG. 8B illustrates an example three-dimensional beamforming network, inaccordance with an example embodiment. The three-dimensional beamformingnetwork has three main components. The three-dimensional beamformingnetwork includes a waveguide input 822, a power dividing section 824, aphase adjusting section 826 (i.e. a three dimensional phase adjustinglens). The three-dimensional beamforming network may not be completelylocated in the same plane of the split-block assembly as the feedwaveguides.

The three-dimensional beamforming network of FIG. 8B may include onlyreactive components. As previously discussed, the use of reactivecomponents may enable the beamforming network to not need the absorptioncomponents that were previously discussed.

The three-dimensional beamforming network may receive electromagneticenergy at the waveguide input 822, ends 828A-828D may be shorts. Thereceived electromagnetic energy may be divided by the three dimensionalpower dividing section 824. The power dividing section 824 may dividethe electromagnetic energy as divided electromagnetic energy based on apredetermined taper profile. The divided electromagnetic energy may haveits phase adjusted by the phase adjusting (three dimensional phaseadjusting lens) section 826. The phase adjustment provided by of eachrespective phase adjusting section 826 may be achieved by theadjustments of heights (i.e. the A dimension) of the waveguide sections,without any changes to widths (i.e. the B dimension) may also be definedbased on the taper profile. The output of the phase adjustment section826 may be coupled to the feed waveguides as shown in FIG. 8C.

The power dividing elements of FIG. 8B of the DOEWG antenna are athree-dimensional dividing network of waveguides. Similar to thetwo-dimensional waveguide of FIG. 8A, the three-dimensional dividingnetwork of waveguides may use waveguide geometry to divide power. Thepredetermined height and width of the feed waveguides may be based on afrequency of operation of the radar unit. The three-dimensional dividingnetwork may include waveguides that differ in height and width from thepredetermined height and width of the feed waveguides in order toachieve the desired taper profile. For example, waveguide 828A and 828Bare shown having a different height.

As discussed above, the three-dimensional dividing network of waveguidesmay be located partly in the common plane 830 as the feed waveguides andpartly in at least one other plane. For example, the entire height of aportion of the three-dimensional dividing network of waveguides may bemachined into either the first or second portion of the split-blockassembly. When the two block pieces are brought together, a surface ofthe other block portion may form an edge of the portion or thethree-dimensional dividing network of waveguides that has its heightfully in one of the two block sections.

FIG. 8C illustrates an example three-dimensional beamforming network, inaccordance with an example embodiment. The three-dimensional beamformingnetwork of FIG. 8C may operate in a similar manner to the previouslydescribed beamforming network of FIG. 8B. The three-dimensionalbeamforming network includes a waveguide input 842, a power dividingsection 844, and a phase adjusting section 846. The three-dimensionalbeamforming network may not be completely located in the common plane849 of the split block construction as the feed waveguides.Additionally, FIG. 8C shows the radiating section 848 that includes thefeed waveguides and the radiating elements. Further, waveguide 848A and848B are shown having a different height.

FIG. 8D illustrates another example three-dimensional unfoldedbeamforming network 850 with short wall coupling elements, designated intwo examples as 854A and 854B, typically shown as one in the inputdesignated as 852A, in accordance with an example embodiment.Additionally, FIG. 8E illustrates an example three-dimensional foldedbeamforming network 860 (i.e. a folded version of FIG. 8D) with shortwall coupling, designated in two examples as 864A and 864B, inaccordance with an example embodiment. This version may be much shorter(in the x-direction) than the unfolded version of FIG. 8D, and may useabsorption load elements to provide termination on the PCB. Thethree-dimensional folded beamforming network with short wall coupling850 and 860 may not use exclusively reactive elements. Thus, thethree-dimensional beamforming network with short wall coupling 850 and860 may use the previously-discussed absorption components.Additionally, the power division and phase shifting may be based on apredetermined taper profile (as previously discussed). Additionally, thewaveguides that form a three-dimensional beamforming network with shortwall coupling 850 and 860 may not all be located in the plane defined bythe feed waveguides (the plane is defined by 852 and 862 respectively).

The dividing and phase shifting provided by three-dimensionalbeamforming network with short wall coupling 850 and 860 may beperformed based on two stacked waveguide sections having short wallsections that are adjacent to each other. When the short walls areadjacent to each other, they may be separated by a thin metal layer toprovide the coupling apertures.

The separation metal layer may be a thin metal layer. The thin metallayer may include a coupling aperture (discussed further with respect toFIG. 8F). The coupling aperture may enable electromagnetic energy tocouple from one waveguide section into another waveguide section that iscoupled to the short walls. In some examples, one waveguide may beformed in a top block of the split block and the other waveguide may beformed in a bottom block of the split block. The thin metal layer may belocated between the two block sections. The three-dimensionalbeamforming network with short wall coupling 850 and 860 may also have aramp section. The ramp section may couple a section of waveguide that isnot in the common plane of the feed waveguides into the common plane ofthe feed waveguides. In another example, the ramp section (shown as 882of FIG. 8F) may couple two adjacent sections of waveguide that are notin the common plane of the feed waveguides into the common plane of thefeed waveguides (shown as 880 of FIG. 8F).

The power dividing elements of FIG. 8D of the DOEWG antenna are athree-dimensional dividing network of waveguides. The three-dimensionaldividing network of waveguides may form hybrid couplers to divide theelectromagnetic energy. As previously discussed, the three-dimensionaldividing network may include waveguides that have a portion of thelength of a respective waveguide adjacent to the length of a portion ofanother waveguide. The waveguides may have adjacent short walls. The twowaveguides may be separated by a thin metal sheet. The coupling aperturemay be formed based on cutouts, holes, or spaces in the thin metal sheetthat allows electromagnetic energy to couple from one waveguide to theadjacent waveguide.

Additionally, in a region that forms a short wall hybrid coupler, afull-height waveguide may be formed in a top block portion and afull-height waveguide may be formed in a bottom block portion. A thinmetal layer may be located at the seam between the two block portions toform both an edge of the respective waveguide of the dividing networkand a coupling aperture. Holes, cuts, perforations, or areas without thethin metal layer may form the aperture by which electromagnetic energymay couple from one waveguide of the dividing network to anotherwaveguide of the dividing network.

FIG. 8F illustrates an example short wall coupler, in accordance with anexample embodiment. The short wall coupler may function in a similarmanner to branch line coupler of FIG. 3A. However, the short wallcoupler is formed between two sections that are aligned verticallyadjacent to each other or can be thought as stacked one on top ofanother with the shared short wall being a thin metal sheet.

Energy may enter the antenna through an input waveguide channel and isdivided (i.e., split) into smaller portions of energy at each powerdivider, such as power divider 870, and may be divided multiple timesvia subsequent power dividers so that a respective amount of energy isfed into each of the feed waveguides. The amount of energy that isdivided at a given power divider may be controlled by a power divisionratio (i.e., how much energy goes into one channel 304 versus how muchenergy goes into another channel 306 after the division). A given powerdivision ratio may be adjusted based on the dimensions of thecorresponding power divider. Further, as previously discussed each powerdivider and associated power division ratio may be designed/calculatedin order to achieve a desired “power taper” at the wave-radiatingchannels.

Within examples, (such as that shown in FIG. 8F) a technique fordividing energy between two vertically adjacent waveguides 874, 876 maybe to use a thin metal layer with a coupling aperture 872 such as thatshown in FIG. 8F. Such a technique and structure design may include anabsorption component such as the terminator the end of a channel, asshown in FIGS. 6A and 6B, or the absorption component of FIG. 5E. Byadjusting the size, shape, and location of the coupling aperture 872,the desired taper profile may be achieved. Further, two adjacentwaveguides, each located in a different split block section may coupleto ramp section 882 to form a single waveguide. The single waveguideafter the ramp section may be located in the common plane of thesplit-block assembly.

It should be understood that other shapes and dimensions of thewaveguide channels, portions of the waveguide channels, sides of thewaveguide channels, wave-directing members, and the like are possible aswell. In some embodiments, a rectangular shape of waveguide channels maybe highly convenient to manufacture, though other methods known or notyet known may be implemented to manufacture waveguide channels withequal or even greater convenience.

It should be understood that arrangements described herein are forpurposes of example only. As such, those skilled in the art willappreciate that other arrangements and other elements (e.g. machines,apparatuses, interfaces, functions, orders, and groupings of functions,etc.) can be used instead, and some elements may be omitted altogetheraccording to the desired results. Further, many of the elements that aredescribed are functional entities that may be implemented as discrete ordistributed components or in conjunction with other components, in anysuitable combination and location.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the scope beingindicated by the following claims.

What is claimed is:
 1. A radar system comprising: a split-block assemblycomprising a first portion and second portion, wherein the first portionand the second portion form a seam, wherein the first portion has a topside opposite the seam and the second portion has a bottom side oppositethe seam; a plurality of ports located on a bottom side of the secondportion; a plurality of radiating elements located on a top side of thefirst portion, wherein: the plurality of radiating elements is arrangedin a plurality of arrays, and the plurality of arrays comprises: a setof multiple-input multiple-output (MIMO) transmission arrays, a set ofsynthetic aperture radar (SAR) transmission arrays, and at least onereception array, and; a set of waveguides in the split-block assemblyconfigured to couple each array to a port.
 2. The radar system accordingto claim 1, further comprising a circuit board coupled to the bottomside of the second portion.
 3. The radar system according to claim 2,wherein the circuit board is configured to provide an electromagneticsignal to at least one of the plurality of ports.
 4. The radar systemaccording to claim 2, wherein the circuit board is configured to receivean electromagnetic signal from at least one of the plurality of ports.5. The radar system according to claim 1, wherein the at least onereception array comprises: a SAR reception array; and a uniform lineararray.
 6. The radar system according to claim 5, wherein the SARreception array is a six by ten array and the uniform linear array is asixteen by ten array.
 7. The radar system according to claim 5, whereinat least one of the uniform linear array and the SAR reception array hasan electronically scanned beam.
 8. The radar system according to claim1, wherein the set of SAR transmission arrays comprises four arrays. 9.The radar system according to claim 7, wherein each SAR transmissionarray is a six by ten array.
 10. The radar system according to claim 1,wherein the set of MIMO transmission arrays comprises four arrays. 11.The radar system according to claim 7, wherein each MIMO transmissionarray is a six by ten array.
 12. The radar system according to claim 1,wherein at least a portion of the set of waveguides have the seam at thecenter of the height of the waveguides.
 13. The radar system accordingto claim 3, wherein at least one waveguide has an edge located at theseam.
 14. The radar system according to claim 1, wherein at least one ofthe ports has dimensions based on impedance matching between a waveguidecoupled to the port and a coupling component coupled to the port. 15.The radar system according to claim 1, wherein the set of waveguidesincludes a plurality of waveguides having edges located at the seam ofthe split-block assembly, wherein each edge is adjacent to an edge ofanother waveguide in the plurality of waveguides.
 16. The radar systemaccording to claim 1, wherein each array comprises a plurality ofradiating elements and a subset of the radiating elements of eachrespective array is coupled to a feed waveguide, and wherein the feedwaveguide has a waveguide feed that is located between two radiatingelements coupled to the feed waveguide.
 17. The radar system accordingto claim 1, wherein each MIMO transmission array has a beam width ofapproximately 90 degrees and each SAR transmission array has a beamwidth of approximately 45 degrees pointed at 22.5 degrees.
 18. The radarsystem according to claim 1, wherein the waveguides form a reactivebeamforming network.
 19. An antenna configuration for a vehicle-mountedradar system comprising: four multiple-output (MIMO) transmissionantenna arrays, wherein each MIMO array is configured as a six by tenarray; four synthetic aperture radar arrays (SAR) transmission antennaarrays, wherein each SAR array is configured as a six by ten array; aSAR reception array configured as a six by ten array; and a uniformlinear array configured as a sixteen by ten array.
 20. A vehicle-mountedradar system comprising: four multiple-output (MIMO) transmissionantenna arrays, wherein each MIMO array has a beam width ofapproximately 90 degrees; four synthetic aperture radar arrays (SAR)transmission antenna arrays, wherein each SAR array has a beam width ofapproximately 45 degrees; a SAR reception array having an electronicallysteerable beam; and a uniform linear array having an electronicallysteerable beam.